An analysis of the relationship between the linear hammer speed and the thrower applied forces during the hammer throw for male and female throwers

The purpose of this study was to investigate the relationship between the cable force and linear hammer speed in the hammer throw and to identify how the magnitude and direction of the cable force affects the fluctuations in linear hammer speed. Five male (height: 1.88 +/- 0.06 m; body mass: 106.23 +/- 4.83 kg) and five female (height: 1.69 +/- 0.05 m; body mass: 101.60 +/- 20.92 kg) throwers participated and were required to perform 10 throws each. The hammer's linear velocity and the cable force and its tangential component were calculated via hammer head positional data. As expected, a strong correlation was observed between decreases in the linear hammer speed and decreases in the cable force (normalised for hammer weight). A strong correlation was also found to exist between the angle by which the cable force lags the radius of rotation at its maximum (when tangential force is at its most negative) and the size of the decreases in hammer speed. These findings indicate that the most effective way to minimise the effect of the negative tangential force is to reduce the size of the lag angle.     

Distributed leadership with the aim of ‘reculturing’: a departmental case study

This article considers a secondary science department that has, since 2000, developed distributed leadership as a form of human capacity building. Using a longitudinal ethnographic case study allowed us to consider how distributed leadership can be nurtured and developed in a department. Our analysis centres on two key issues: the nature and pattern of distributed leadership practices and the continuity that provides coherence to those practices. From our analysis, there appear to be two major conclusions. The first of these is the need for administrators to be purposeful in the appointments that they make to formal leadership positions. To enact distributed leadership practices requires leaders who can exercise both formal power and influence. The second conclusion relates to the time required for continuity of leadership practices to give rise to changes that lead to teachers managing the teaching and learning programme.     

Centrality of enactive experiences,framing, and motivation to student teachers’ emerging professional identity

Professional identity has emerged as a common theme in teacher development research, and the student-teaching practicum is often identified as foundational to identity development. In the context of the student-teaching practicum, interactions with cooperating teachers and pupils are believed to comprise the press for professional identity development, though theory-based explanations are often neglected in the literature, and findings are not always consistent. To address this issue, we used grounded theory to articulate a model explaining the relations among three constructs important to the process of identity development of student teachers (n = 14). Our findings are organized around a model that highlights the phenomenon of “negotiating who I am as a teacher,” which helps us describe differences between student teachers who changed identity vs. those that did not, and psychological and contextual reasons for renegotiation of identity. Discussion focuses on comparisons with previous models and possible implications for teacher education.     

Understanding Biological Evolution Through Computational Thinking

Science & Education - Computational thinking is a contemporary science and engineering practice that has been introduced to the US science classrooms due to its emphasis in the Next Generation...     

Reading ability and memory span: Long-term memory contributions to span for good and poor readers

A number of studies have shown that childrenwith reading difficulties perform poorly ontests of verbal memory span. The extent towhich differences in memory span for good andpoor readers can be explained by differences ina long-term memory component to span as well asby differences in short-term memory processeswas investigated in this study. Memory spanand rehearsal rate were measured for high andlow frequency words and nonwords. Althoughmemory span performance for high frequencywords was comparable for all reading abilitygroups, good readers had better memory spanperformance for low frequency words. This wasattributable to differences in both short-termand long-term memory contributions to spanperformance. Differences between readingability groups also emerged when memory spanfor nonwords was measured. In this case,differences between groups also appeared to bethe result of difficulties which poor readersencountered in learning newphonologically-based materials (i.e. nonwords). The nature of the inter-relationships betweenmemory span, reading and measures ofphonological awareness are discussed in thelight of these findings.     

The ontogeny of the feature-positive effect in young chicks

The wide generality of the feature-positive effect (FPE) has caused speculation that the FPE may represent innate biases in the stimulus control of discriminative responding. There is little experimental evidence to date ragarding this possibility. In the present study, 1- or 4-day-old chicks were trained on a feature-positive (FP) or feature-negative (FN) discrimination with heat reinforcement. After the acquisition phase, these subjects received extinction training followed by a reacquisition phase. The FP performance was superior to the FN performance in both age groups. Extinction resulted in improved discrimination performance in both the FP and FN conditions. Unmasking of FN learning by the extinction treatment suggests that the FPE represents a deficit in performance, rather than an inability to learn the FN task. These data demonstrate that adult-like performance on feature discriminations is evident as early as the first day post-hatch.